The present study focuses on the thermomechanical investigation of bioplastic firms produced from a combination of polylactic acid (PLA) and nano-calcium carbonated (nano-CaCO3) synthesized from the Achatina Fulica snail shell. The bioplastic films fabricated with nano-CaCO3 content ranging from 1 to 5 wt% were prepared using a solvent casting method. Thermal stability and degradation with temperature-dependent mechanical properties such as stiffness, storage modulus, and loss modulus of the developed bioplastic films were determined. The conformation changes in the functional group of the developed bioplastic films after incorporating nano-CaCO3 were also investigated. It was observed that incorporating nano-CaCO3 improved the thermal stability and temperature-dependent mechanical properties of neat PLA, regardless of the percentage weight added. An 85.67% improvement in thermal stability was observed. The temperature-dependent stiffness increased by 84%, whereas the storage modulus improved by 240%. On the other hand, loss modulus improved by 50% due to nano-CaCO3 incorporation into PLA. The FTIR curves of bioplastic films incorporated with nano-CaCO3 present insignificant conformation changes in the functional group of the resulting bioplastic films. This is presumable due to the compatibility of the matrix and the reinforcement. As a result, the resulting materials' thermal and temperature-dependent mechanical properties improved significantly, demonstrating that the developed bioplastic films could be used for package applications.